Blade stabilizer for motor grader



June 29, 1965 M. E. BEYERS ETAL 3,191,324

BLADE STABILIZER FOR MOTOR GRADER Filed June 13, 1963 2 Sheets-Sheet 1 J INVENTORB Z3 zz MRI/W E. BEYERS BY JoH/v W CARTER WNW! ATTORNEYS June 29, 1965 M. E. BEYERS ETAL 3,191,324

BLADE STABILIZER FOR MOTOR GRADER Filed Jun 15, 1965 2 Sheets-Sheet z INVENTORS [WARM/v5 BEYERLS Jomv W CARTER AT ORNEYS' 3,191,324 BLADE STABILIZER FOR MOTOR GRADER Marvin E. Beyers and John W. Carter, Peoria, 111., assignors to Caterpillar Tractor Co., Peoria, 111., a corporation of California Filed June 13, 1963, Ser. No. 287,633 1 Claim. (C1. 37-156) This invention relates to means for stabilizing or suppressing bounce in grading machines of the rubber tired type, such for example as a motor grader.

Finish grades for roads or other projects requiring a relatively high level of precision are most economically obtained through high speed rubber tired machines. While the wheel or rubber tire type of earthmoving and grading machine is capable of high speeds compared with track-type machines, considerable bounce is experienced especially in light work such as finish grading. Frequently such bouncing is accentuated by resonancy and becomes so severe that an unacceptable grade is produced and it is necessary to operate at a reduced speed and in some cases to make a second cut to correct the grade deficiency created by a bouncing blade.

It is an object of the present invention to provide means to counteract the tendency of rubber tired machines to bounce and thereby to stabilize the blade of such a machine in order to produce an accurate grade at high speed operation.

A further object of the invention is to provide a skid or pressure plate engageable with the earth directly behind the cutting blade of a grading machine of the kind referred to and to provide means for exerting variable downward force to such a plate to attain a desired stabilizing effect in different types of soil or material being graded.

Further and more specific objects and advantages of the invention are made apparent in the following specification wherein the invention is described in detail by reference to the accompanying drawings.

In the drawings: a

FIG. 1 is a view in side elevation of a motor grader equipped with a blade stabilizer embodying the present invention;

FIG. 2 is an enlarged fragmentary view of the motor grader blade and stabilizer shown in FIG. 1; and

FIG. 3 is a fragmentary view from the left or rear of the mechanism illustrated in FIG. 2.

The motor grader illustrated in FIG. 1 of the drawings is typical of various rubber tired machines with a blade usable for grading and subject to bouncing action during high speed operation because of the resiliency of the tires. The motor grader, generally shown at 10, is of conventional construction have a forward frame 11 beneath which a draft assembly is arranged. The draft assembly comprises a drawbar structure 12, a blade supporting ring 13 and a pair of spaced draft beams, only one of which is shown as extending downwardly therefrom as at 14. A working blade 15 is also conventionally supported by the lower ends of the draft beams. The blade is arranged for lateral sliding movement in the supporting frame 16 by means not pertinent to the present invention and the frame 16 has rearwardly extending bearings 17, best shown in FIG. 3, pivotally mounted on the opposite ends of a shaft 18 which extends between the lower ends of the draft beams 14 and projects beyond the beams to provide supporting journals for the bearings 17. This enables forward and rearward tilting of the blade which may be held in its properly adjusted position by a quadrant 19 extending rearwardly from the frame 16 and secured in any position of adjustment as by a bolt 20 which secures the quadrant against the side of the draft beam as shown.

The present invention pertains to means to prevent bouncing which causes the blade 15, normally operating in the position shown in FIGS. 1 and 2, to dig into the ground beyond its intended depth and rise out of the ground beyond its proper level to produce an uneven or corduroy surface unacceptable for finish grading. The invention comprises a skid plate, generally indicated at 22 in the drawings, and having a ground engaging surface 23 adapted to be raised and lowered with respect to the surface of the ground and the elevation of the cutting edge of the blade 15. The skid plate extends throughout substantially the full length of the blade 15 and is disposed behind it as shown. Adjacent opposite ends of the skid plate a pair of hydraulically actuated jacks of the double acting type, one of which is shown at 24 in FIGS. 2 and 3, are pivotally supported on brackets 25 which extend outwardly from the upper ends of the draft beams 14. Extensible rods 27 of the jacks 24 are pivotally connected to brackets 28 secured to the skid plate. The skid plate is supported for raising and lowering movement by pairs of links, one pair of which is shown at 30 and 31 in FIG. 2. The link 30 is pivotally connected to brackets 33 (see also FIG. 3) which are secured as by welding to a tube 34 which houses the shaft 18 and is secured at its opposite ends to the draft beams 14. The opposite end of the link 30 is pivotally connected to a bracket 35 on the skid plate. The link 31 is similarly connected to the skid plate through a bracket 36 and pivoted at its upper end to a pin 37K which is welded to and projects outwardly from a plate 38. This plate 38 is secured as by cap screws to a bracket 39, best shown in FIG. 3, welded to the outer face of the draft beam 14. The plate extends forwardly and downwardly and is strengthened at its forward end by embracing the terminal end of the shaft 18 where it projects beyond the bearing 17 as best shown in FIG. 3, the plate 38 having a bore to receive the end of the shaft as shown in 42 in FIG. 1. While the links 30 and 31 maybe of the same length, their pivotal supports are out of parallelism, the forward pivot of the link 30 being disposed slightly below the forward pivot of the link 31. Consequently upon actuation of the jack 24 to raise the skid plate, it assumes the position illustrated in broken lines at 23a in FIG. 2 having swung rearwardly and upwardly upon its pivoted link support to an angled position sufficiently above and rearwardly of the blade 15 to permit various adjustments of the blade without interference. However, because of the arrangement of pivots with the front pivots only slightly varied in height, movement of the skid plate near the ground will be substantially parallel to the ground so that it can be raised and lowered for adjustment purposes and still be effective as a skid plate.

Hydraulic fluid is supplied to opposite ends of the jacks selectively from a source of fluid under pressure (not shown) and through conduits 43 in a well known manner. Consequently with a suitable control valve disposed at the operators station of the motor grader, the skid plate may be raised and lowered at will and fixed in any desired position. The precise position of the skid plate and therefore the pressure exerted against the ground will depend upon the nature of the soil in which grading is being done and sufficient pressure may be applied in any event to stabilize the blade against vertical bounce resulting from the compressibility of the rubber tires upon which the machine is supported. As a consequence of the construction herein disclosed, a motor grader or similar rubber tired grading machine may operate at much greater speeds than is otherwise possible with assurance that a good grade will be accomplished without the usual bounce which results from the resilient support of the machine.

Since the skid plate and adjusting means therefore are supported entirely by the draft beams which depend from and move with the blade circle, it will follow the cutting blade in all positions of adjustment imparted to the blade through the circle.

We claim:

The combination with a grading machine of the rubber tired type having a grading blade with a cut-ting edge engageable with the ground, a skid plate of substantially the same length as the blade, means supporting the skid plate for contact with the ground rearwardly of the blade,

I means for adjusting the skid plate in a substantially vertical direction to reduce bounce of the machine and blade with respect to the ground, the means for supporting the skid plate comprising two sets of two links of equal lengths connecting the skid plate and the draft beam, a forward link of each set having a pivotal connection-With the draft frame and extending rearwardly and downwardly to a pivot near the forward edge of the skid plate when the plate is on the ground, a rearward link of each set having a pivotal connection with the draft frame and extending rearwardly and downwardly to a pivot near the rear edge of the skid plate, and said rearward link pivotal connection with the draft frame being slightly lower than the forward one, whereby slight vertical adjustment may be made with the skid plate in a substantially horizontal position, and greater raising movement will effect upward swinging of the skid plate toward a substantially vertical position behind the blade.

References Cited by the Examiner UNITED STATES PATENTS T. GRAHAM CRAVER, Primary Exai'niner. BENJAMIN HERSH, Examiner. 

